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Check your new coil

Posted: Fri May 29, 2009 6:29 pm
by autolycus
Because I was a bit dubious about the coil-of-unknown-origin on my non-Moggy wedding car, I bought a couple of new ones from Paddock Spares, the Land Rover people. Series Land Rovers use 12v, non-ballasted coils like many other cars of the 50s and 60s.

The new coil lasted about 10 miles before the car began hesitating under load. At 15 miles, the car failed to proceed, and the coil was too hot to touch. The equally new spare got me home, just.

Checking the primary resistance showed around 1.6-1.7 ohms on both of these coils and the unused one I'd reserved for another car. This is about right for coils designed for use with a ballast resistor. 12v coils are normally around 3.2 - 3.6 ohms, I believe.

These coils were unbranded, in plain white boxes, , but bear a remarkable resemblance to those now sold as Lucas. Lucas now simply licence their name, it seems, to be used on various products.

Moral: get that digital multimeter on your new or newish coil. If it's a standard system, and your coil resistance is under 2 ohms, it willbreak down - it's just a matter of how soon.

YRMV (resistance)

Kevin

Posted: Fri May 29, 2009 8:30 pm
by bmcecosse
Yes - 12 volt coil should be ~ 3.5 ohms, and the lower voltage 6 or 9 volt colis are ~ half that as you have found. But I'm surprised at Paddock - they have a good reputation in the Triumph world!

Posted: Fri May 29, 2009 8:30 pm
by rayofleamington
With your luck it would be better to buy a ballast resistor!

I am tight and use second hand original coils. I must be lucky as I've not had one fail (ever), but having a spare that only cost a few quid is probably better than paying full whack for one that's not fit for purpose.

Posted: Fri May 29, 2009 8:32 pm
by bmcecosse
Ray has a good point there - if you install the ballast resistor and suitable bypass arangement when starting - you will have much better 'assured' starting. This was done on the Mini when the compression ratio was lifted to improve the economy.

Posted: Fri May 29, 2009 9:01 pm
by autolycus
You're right, Ray, I'm not having much luck with this car at the moment. Only yesterday a factory genuine rotor arm (now like hens' teeth, and 40 quid for a replica one) failed on me - tracking through the body of the plastic to earth via the distributor shaft.

In 45 years of maintaining cars I've never previously bought a brand new coil - and I've learned my lesson now - but whereas rummaging through the boot trying assorted plugs, points, condensers, and coils is generally fine, it's a bit embarrassing with a bride and her dad in the back.

The car had a 6v coil when I bought it, with a ballast resistor shorted out for starting with a relay, but I had so many intermittent electrical problems, and virtually every crimped connection earlier owners had made was faulty (damned insulated crimps), so I decided to go back to the simple layout that had worked for 50 years. The car is very cossetted, and always garaged. I'll be scouring Wollaton autojumble on Sunday looking for NOS Lucas coils.

There are two (unconnected?) Paddocks - James, the Triumph lot, and AEW Paddock Motors, in Matlock, the Land Rover people, who also have an excellent reputation. Just not for coils any longer.

Kevin

Posted: Fri May 29, 2009 9:59 pm
by bmcecosse
Ahhh -it's James P I'm familiar with! Thanks for clearing that up!